All themes are application specific.
In order to use a Theme, create a folder that defines it.
This folder needs to be placed in a folder named App_Themes, which must be placed inside the top-level directory for your web application.
For example, if application is called SuperCommerce and the theme is FunkyTheme, it should stay in SuperCommerce\App_Themes\FunkyTheme.
Only one theme can be active on a given page at a time.
A skin file is a text file with the .skin extension.
ASP.NET treats all the skin files in a theme directory as part of the same theme definition.
To apply the theme, set the Theme attribute of the Page directive to the folder name.
<%@ Page Language="C#" AutoEventWireup="true" ... Theme="FunkyTheme" %>